THE CHURCH OF S. SAVIOUR IN THE CHORA 307
•of a cross on the aureola. The spaces at the sides of the medallion are filled in with a pierced scroll showing a dark :slab of porphyry behind it, making a very beautiful arrangement. These frames are distant from the eikonostasis, which •stretched across the front of the bema arch, nearer to the apse, On the south side are two doors leading to the parecclesion, and on the north side above the cornice is a small window from the north gallery.
The. dome rests on a ribbed drum of sixteen concave segments, and is pierced by eight windows corresponding to the octagonal form of the exterior. The original crown has fallen and been replaced by the present plain Turkish dome. The prothesis and the diaconicon are represented by chapels to north and south of the apse* As already stated, they do not now communicate with the bema, although the position of the old passages between them and the bema is marked by niches in the marble revetment. From the fact that the Byzantine marble work is continued across these passages it is evident that the chapels were cut off from the apse in Byzantine days. The north chapel is covered by a drum dome of eight concave sections, and is entered from the lower •story of the gallery on the north side of the church. It •should be noticed that the chapel is not placed axially to this gallery. The south chapel is covered by a plain drum dome, and is now entered from the parecclesion, evidently as the result of the alterations made when the parecclesion was added.
The exterior is very simply treated. The side apses show three sides of an octagon. The central apse has five isides of a very flat polygon, and is decorated with hollow niches on each side of a large triple window. It was at one time supported by a large double flying buttress, but the lower arch has fallen in. As the buttress does not bond with the wall it was evidently a later addition.
The inner narthex is entered from the outer narthex by a door to the west It is with its resplendent marble revetment and brilliant mosaics a singularly perfect and beautiful piece of work, one of the finest gems of Byzantine art It is divided into four bays, and is not symmetrically